Method for fabricating semiconductor device with redistribution structure

Abstract

The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a first chip including: a first inter-dielectric layer positioned on a first substrate; a plug structure positioned in the first inter-dielectric layer and electrically coupled to a functional unit of the first chip; a first redistribution layer positioned on the first inter-dielectric layer and distant from the plug structure; a first lower bonding pad positioned on the first redistribution layer; and a second lower bonding pad positioned on the plug structure; and a second chip positioned on the first chip and including: a first upper bonding pad positioned on the first lower bonding pad; a second upper bonding pad positioned on the second lower bonding pad; and a plurality of storage units electrically coupled to the first upper bonding pad and the second upper bonding pad.

What is claimed is: 
     
       1. A method for fabricating a semiconductor device, comprising:
 providing a first substrate comprising a functional unit; 
 forming a plug structure on the first substrate and electrically coupled to the functional unit; 
 forming a first redistribution layer above the first substrate; 
 extending a top surface of the plug structure through a bottom surface of the first redistribution layer; 
 forming a first lower bonding pad on the first redistribution layer; 
 forming a second lower bonding pad on the plug structure, wherein the first substrate, the plug structure, the first redistribution layer, the first lower bonding pad, and the second lower bonding pad together configure a first chip; 
 forming a third barrier layer between the plug structure and the second lower bonding pad; 
 forming a U-shaped protrusion at a bottom surface of the third barrier layer and extending the U-shaped protrusion of the third barrier layer through a top surface of the first redistribution layer in order to contact with the top surface of the plug structure, such that a contact between the plug structure and the third barrier layer is located between the top surface and the bottom surface of the first redistribution layer; and 
 bonding a second chip onto the first chip, wherein the second chip comprises a first upper bonding pad bonded on the first lower bonding pad, a second upper bonding pad bonded on the second lower bonding pad, and a plurality of storage units electrically coupled to the first upper bonding pad and the second upper bonding pad. 
 
     
     
       2. The method for fabricating the semiconductor device of  claim 1 , wherein the first chip is configured as a logic chip and the second chip is configured as a memory chip, and the plurality of storage units are configured as capacitor array or floating array. 
     
     
       3. The method for fabricating the semiconductor device of  claim 1 , wherein the plug structure comprises a bottom plug formed on the first substrate, a landing pad formed on the bottom plug, and a top plug formed on the landing pad, wherein the method further comprising extending a top surface of the top plug through the bottom surface of the first redistribution layer to contact with the U-shaped protrusion of the third barrier layer. 
     
     
       4. The method for fabricating the semiconductor device of  claim 3 , further comprising forming a first barrier layer between the top plug and the second lower bonding pad. 
     
     
       5. The method for fabricating the semiconductor device of  claim 3 , further comprising forming a second barrier layer between the landing pad and the top plug. 
     
     
       6. The method for fabricating the semiconductor device of  claim 3 , further comprising forming a fourth barrier layer between the first lower bonding pad and the first redistribution layer, and configuring the fourth barrier layer to have a U-shaped cross-sectional profile to receive the first lower bonding pad therewithin. 
     
     
       7. The method for fabricating the semiconductor device of  claim 6 , wherein a bottom surface of the U-shaped protrusion of the third barrier layer is at a vertical level lower than the top surface of the first redistribution layer. 
     
     
       8. The method for fabricating the semiconductor device of  claim 3 , wherein a width of the first chip and a width of the second chip are the same. 
     
     
       9. The method for fabricating the semiconductor device of  claim 3 , wherein the bottom plug comprises aluminum, copper, or a combination thereof, and the top plug comprises tungsten. 
     
     
       10. The method for fabricating the semiconductor device of  claim 7 , wherein the third barrier layer comprises titanium and titanium nitride. 
     
     
       11. The method for fabricating the semiconductor device of  claim 10 , wherein the plurality of storage units are configured as a capacitor array or a floating array. 
     
     
       12. The method for fabricating the semiconductor device of  claim 1 , wherein a width of the first upper bonding pad is larger than a width of the first lower bonding pad, wherein a width of the second upper bonding pad is larger than a width of the second lower bonding pad. 
     
     
       13. The method for fabricating the semiconductor device of  claim 1 , wherein the third barrier layer has the bottom surface in direct contact with the top surface of the first redistribution layer. 
     
     
       14. The method for fabricating the semiconductor device of  claim 1 , wherein the width of the second upper bonding pad is equal to a width of the third barrier layer. 
     
     
       15. The method for fabricating the semiconductor device of  claim 6 , wherein the width of the first upper bonding pad is equal to a width of the fourth barrier layer. 
     
     
       16. The method for fabricating the semiconductor device of  claim 1 , wherein the third barrier layer is disposed between the plug structure and the second lower bonding pad by the steps of:
 forming a protrusion portion at a bottom of the second lower bonding pad toward the plug structure; and 
 forming the third barrier layer to have a U-shaped cross-sectional profile to receive the second lower bonding pad therewithin, wherein the protrusion portion of the second lower bonding pad is received in the U-shaped protrusion of the third barrier layer when the second lower bonding pad is received in the third barrier layer.